1. Field of the Invention
The present invention relates generally to a circuit-terminal connecting device, and more particularly to an improvement in a circuit-terminal connecting device used for connecting first circuit-terminals provided on a mail circuit board with second circuit-terminals provided on a flat circuit member, such as a flexible printed circuit board (hereinafter, referred to as an FPC), which is laid on top of the main circuit board.
2. Description of the Prior Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
There has been proposed, for the purpose of saving a space in an electronic apparatus, to lay a flat circuit member, such as a relatively small-sized FPC, on top of a main circuit board on which various electrical or electronic parts are mounted when the flat circuit member is electrically connected with the main circuit board in the electronic apparatus. Such an electrical connection between the main circuit board and the flat circuit member wherein the flat circuit member is laid on top of the main circuit board is hereinafter referred to as an electrical piling connection.
There has been also proposed a board connecting device comprising a first connector fixed to a main circuit board, on top of which an FPC is laid, and a second connector fixed to an FPC to be coupled with the first connector when the main circuit board and the FPC are put in an electrical piling connection, as disclosed in, for example, the Japanese patent application published before examination under publication number HEI 9-312183 (hereinafter, referred to as a published prior art document 1) or the Japanese patent application published before examination under publication number 2007-258001 (hereinafter, referred to as a published prior art document 2). With the second connector coupled with the first connector, a plurality of first circuit-terminals provided on the main circuit board are connected respectively with a plurality of second circuit-terminal provided on the FPC through the first and second connectors.
In the board connecting device disclosed in the published prior art document 1, a first connector (a mate connector (110)) having a plurality of contacts (112) is caused to stand on a main circuit board (a printed circuit board (2)) having a plurality of first circuit-terminals (land patterns) provided thereon in such a manner that the contacts of the first connector are soldered respectively to the first circuit-terminals on the main circuit board, and a second connector (a printed circuit board connector (10)) having insulated base-housing (20) and an insulated cover-housing (30) provided for engaging with the first connector is fixed to a FPC (a flexible board (1)) having a plurality of second circuit-terminals (terminals (1b)) arranged in parallel with one another thereon. The FPC is bent along an arrangement of the second circuit-terminals to be held between the insulated base-housing and the insulated cover-housing so that the second circuit-terminals are exposed to the outside on the insulated base-housing.
The FPC to which the second connector is fixed is caused to face and approach to the main circuit board on which the first connector is caused to stand in such a manner that the second connector is positioned to correspond to the first connector. Then, the second connector fixed to the FPC is coupled with the first connector on the main circuit board so that the second circuit-terminals, which are exposed to the outside on the insulated base-housing of the second connector, come directly into contact respectively with the contacts of the first connector to be connected with the same. Therefore, the main circuit board and the FPC are electrically connected with each other in the form of the electrical piling connection, and the second circuit-terminals on the FPC are connected respectively with the first circuit-terminals on the main circuit board through the first and second connectors.
With the board connecting device disclosed in the published prior art document 1 as mentioned above, the second connector fixed to the FPC can be designed without any contact provided thereon for electrical connection with the first connector on the main circuit board.
Further, in the board connecting device disclosed in the published prior art document 2, a first connector (a mate connector (30)) having a plurality of terminals (34) is fixed to a main circuit board (a circuit board (P)) having a plurality of first circuit-terminals (corresponding circuit portions) provided thereon in such a manner that the terminals of the first connector are soldered respectively to the first circuit-terminals on the main circuit board, and a second connector (a connector (10)) having a plurality of terminals (12) is fixed to an FPC (a flexible board (F)) having a plurality of second circuit-terminals (corresponding circuit portions) provided thereon in such a manner that the terminals of the second connector are soldered respectively to the second circuit-terminals on the FPC. On an outer surface of the first connector, a plurality of contacting portions (35) of the terminals of the first connector are arranged to be exposed to the outside. The second connector is provided with a hole (14) formed thereon so that the first connector fixed to the main circuit board fits into the hole on the second connector fixed to the FPC. Around the hole provided on the second connector, a plurality of contacting portions (12B1) of the terminals of the second connector are arranged to be exposed to the hole. One of mutually opposite openings of the hole on the second connector fixed to the FPC is covered closely by the FPC.
The FPC to which the second connector is fixed is caused to face and approach to the main circuit board to which the first connector is fixed in such a manner that the hole provided on the second connector is positioned to correspond to the first connector. Then, the first connector fixed to the main circuit board is caused to fit into the hole provided on the second connector fixed to the FPC so that the second connector is coupled with the first connector, and the contacting portions of the terminals of the second connector, which are arranged around the hole provided on the second connector to be exposed to the hole, come directly into contact respectively with the contacting portions of the terminals of the first connector, which are arranged on the outer surface of the first connector to be exposed to the outside, to be connected with the same. Therefore, the main circuit board and the FPC are electrically connected with each other in the form of the electrical piling connection, and the first circuit-terminals on the main circuit board are connected respectively with the second circuit-terminals on the FPC through the first and second connectors.
When the main circuit board and the FPC are put in the electrical piling connection with the previously proposed board connecting device disclosed in the published prior art document 1 and the first circuit-terminals on the main circuit board are connected respectively with the second circuit-terminals on the FPC, the second connector fixed to the FPC is laid on top of the first connector caused to stand on the main circuit board. Thereby, a distance between the main circuit board and the FPC is made relatively large so that it is undesirably impeded to reduce a thickness of a structure on the whole comprising the main circuit board, the first connector, the second connector and the FPC.
Further, when the FPC to which the second connector is fixed is caused to face and approach to the main circuit board on which the first connector is caused to stand and then connected electrically with the main circuit board so that the main circuit board and the FPC are put in the electrical piling connection, both of the first connector on the main circuit board and the second connector fixed to the FPC are covered by the FPC so as not to be observed from the rear side of the FPC. Accordingly, a handling operation for coupling correctly the second connector fixed to the FPC with the first connector on the main circuit board so as to put the main circuit board and the FPC in the electrical piling connection becomes awkward and it is difficult to confirm visually a condition wherein the main circuit board and the FPC are surely put in the electrical piling connection.
Besides, the board connecting device disclosed in the published prior art document 1 is not provided with any means for locking the second connector coupled with the first connector on the main circuit board and therefore there is a disadvantage that it is difficult for the subject board connecting device to maintain the electrical piling connection between the mail circuit board and the FPC to be stable.
In the previously proposed board connecting device disclosed in the published prior art document 2, the hole into which the first connector fixed to the main circuit board fits are formed on the second connector fixed to the FPC and thereby the second connector fixed to the FPC is not laid on top of the first connector fixed to the main circuit board when the main circuit board and the FPC are put in the electrical piling connection with the board connecting device disclosed in the published prior art document 1. Accordingly, it is possible for the board connecting device disclosed in the published prior art document 1 to make a distance between the main circuit board and the FPC relatively small so as to avoid a situation wherein reduction in a thickness of a structure on the whole comprising the main circuit board, the first connector, the second connector and the FPC is undesirably impeded.
However, in the case of the board connecting device disclosed in the published prior art document 1 also, when the FPC to which the second connector is fixed is caused to face and approach to the main circuit board to which the first connector is fixed and then connected electrically with the main circuit board so that the main circuit board and the FPC are put in the electrical piling connection, both of the first connector fixed to the main circuit board and the second connector fixed to the FPC are covered by the FPC so as not to be observed from the rear side of the FPC. Consequently, a handling operation for coupling correctly the second connector fixed to the FPC with the first connector fixed to the main circuit board so as to put the main circuit board and the FPC in the electrical piling connection becomes awkward and it is difficult to confirm visually a condition wherein the main circuit board and the FPC are surely put in the electrical piling connection.
Further, the board connecting device disclosed in the published prior art document 2 is not provided with any means for locking the second connector coupled with the first connector on the main circuit board and therefore there is an disadvantage that it is difficult for the subject board connecting device to maintain the electrical piling connection between the mail circuit board and the FPC to be stable, in the same manner as the case of the board connecting device disclosed in the published prior art document 1.